JSFiddle - React, Tailwind, and code Playground
HTML
<link rel="stylesheet" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8/themes/dot-luv/jquery-ui.css">
<textarea id="txtarr">
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</textarea>JavaScript
var valuetxtarr = $("#txtarr").val();
var valuetxtarrs = valuetxtarr.replace(/\n/g,",");
alert(valuetxtarrs);